Manufacturing method for magnetic head junction board

ABSTRACT

A method of manufacturing a magnetic head junction board wherein a laminated plate having a springy metal layer and a conductive layer is prepared. A circuit wiring pattern is formed on the conductive layer by photoetching and the springy metal layer is formed into a predetermined shape by etching. The circuit wiring pattern is provided with a surface protecting layer which leaves holes exposed at the ends of the circuit wiring pattern. Then, the holes are filled with conductive metal to form bump-shaped terminals such that the ends on one side jut out of the surface protecting layer. Lastly, the springy metal layer is bent into a predetermined shape so that the bump-shaped terminals face against each other. Alternative process are also disclosed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a magnetic head junction board which isuseful as a means for electrically connecting a wiring pattern on amagnetic head suspension, which is used for a magnetic disk unit or thelike, and a wiring pattern on a read/write amplifier substrate and amanufacturing method for the same.

2. Description of the Related Art

This type of magnetic disk unit is equipped with at least a singlerotary disk for magnetically recording information, a magnetic headdevice for reading data from or writing data to the tracks on the disk,and a head positioning actuator which is connected to the head device tomove the head device to a desired track and which also holds the headdevice above the track.

A conventional magnetic head suspension assembly has been disclosed, forexample, in Japanese Patent Laid-Open No. 63-113917. In the disclosedart, the magnetic head device is attached to gimbals with epoxy resin orthe like and the gimbals is attached to a suspension by means of laserwelding or the like. A gold plated copper wire and the like providedwith urethane coating or the like is connected by ultrasonic welding orsoldering or the like to an electrode formed on a magnetic head device,thereby constituting the component of a leader wire for a signal to anexternal circuit. The leader wire component is turned a predeterminedtimes into a coil and contained in a flexible tube made of insulatingresin and the tube is installed on the suspension by crimping a part ofthe suspension or by other similar means.

In such a magnetic head suspension assembly, the connection between theelectrode on the magnetic head device and the leader wire is extremelyinefficient because of restricted workability, making it difficult toachieve higher productivity. The recent increasing number of terminalsdue to the decreasing sizes of magnetic head devices and the increasinguse of MR devices are making the problem more serious. There is anotherproblem in that the rigidity of the aforesaid leader wire componentadversely affects the levitation of the magnetic head device, preventingthe achievement of an optimum levitation attitude thereof. Further, theleader wire component is subjected to the wind pressure due to the airflow induced by the rotation of the recording medium, also adverselyaffecting the levitation attitude of the magnetic head device.

To solve the problem stated above, Japanese Patent Laid-Open No.4-219618 has disclosed an art which provides a suspension made integralwith circuit wiring which combines a leader wire component and asuspension mechanism.

In this art, however, a lead wire used for connecting a magnetic headdevice and an amplifier as in the past is used for an electrical meansfor connecting a circuit wiring pattern, which is formed integrally onthe suspension, and a read/write amplifier substrate. This connectingmeans makes it difficult to achieve reduced cost by automation as it didwhen it was previously used for the connection with the magnetic headdevice.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide amagnetic head junction board ideally suited as a means for configuringan inexpensive magnetic recording unit by permitting automatedelectrical connection between the circuit wiring on a magnetic headsuspension, which combines the circuit wiring and the suspension intoone piece via a flexible insulating layer, and a read/write amplifiersubstrate, and a manufacturing method for the same.

To this end, according to the present invention, there is provided amagnetic head junction board equipped with a flexible circuit board, theends of which are uniformly connected to the inside of a springy metallayer, which has been bent to a U shape having a predetermined width,and the rest of which extends in a predetermined width outward from thespringy metal layer, wherein the flexible circuit board is equipped withbump-shaped connecting terminals on the opposed bent sections, the endson one side of which are electrically connected to the ends of thecircuit wiring patterns formed on the flexible circuit board and theends on the other side of which jut outward. The connecting terminalsare electrically connected to the terminal of the magnetic headsuspension, which is made integral with circuit wiring, by the clampingforce of the springy metal layer, thereby permitting the electricalconnection between the magnetic head suspension and the read/writeamplifier substrate. This magnetic head junction board enables theflexible circuit board to provide a surface protecting layer forcovering the circuit wiring pattern in the area excluding the juttingconnecting terminals.

The magnetic head junction board can be produced according to thefollowing process. A laminated plate is prepared, in which one surfaceof the flexible insulating base material has a springy metal layer andthe other surface has a conductive layer. A desired circuit wiringpattern is formed on the conductive layer of the laminated plate byphotoetching or other similar means and the springy metal layer isformed into a predetermined shape by etching. The outer surface of thecircuit wiring pattern is provided with a surface protecting layer byusing a photosensitive resin or the like to make holes to partly exposethe ends of the circuit wiring patterns at the sections which correspondto both ends of the springy metal layer. Then, the aforesaid holes arefilled with conductive metal by plating or the like to form bump-shapedterminals, the ends on one side of which are electrically connected tothe circuit wiring patterns and the ends on the other side of which jutout of the surface protecting layer. Lastly, the springy metal layer isbent to a predetermined shape so that the aforesaid connecting terminalsface against each other.

According to another process for fabricating the magnetic head junctionboard, a groove matching a predetermined configuration is formed in thespringy metal layer when producing the circuit wiring pattern. Then, thesurface protecting layer is formed and the bump-shaped connectingterminals are formed. After that, an excimer laser beam is radiated fromthe groove side to ablate the portions of the flexible insulating basematerial and of the surface protecting layer which are positioned in thearea of the groove so as to obtain the predetermined configuration.Lastly, the springy metal layer is bent to the predetermined shape asstated above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual perspective view of an essential section of amagnetic head junction board in an embodiment according to the presentinvention;

FIG. 2 is a conceptual cross-sectional view taken on line X--X shown inFIG. 1;

FIG. 3 is an explanatory diagram showing the magnetic head junctionboard in accordance with the present invention which is to be attachedto a suspension made integral with circuit wiring;

FIG. 4A through FIG. 4D show the manufacturing process steps accordingto an embodiment for fabricating the magnetic head junction board inaccordance with the present invention; and

FIG. 5A through FIG. 5E show the manufacturing process steps accordingto another embodiment for fabricating the magnetic head junction boardin accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will now be described in detailwith reference to the accompanying drawings. FIG. 1 is the conceptualperspective view of the essential section of the magnetic head junctionboard according to an embodiment of the present invention. As it is seenfrom the cross-sectional view of FIG. 2 taken on line X--X, a flexibleinsulating base material 1 which uses an appropriate component such as apolyimide film is formed in approximately T shapes in a spread state.Formed around the end outer surface of the flexible insulating basematerial 1 is a springy metal layer 2 in a predetermined width which ismade of a phosphor bronze plate, stainless plate, or the like which hasbeen formed to have a U-shaped cross section.

Desired circuit wiring patterns 3 are formed on the other outer surfaceof the flexible insulating base material 1 by etching the conductivelayer made of copper foil or the like. In this embodiment, four circuitwiring patterns 3 are terminated at the locations which correspond tothe opposed surfaces of the bent springy metal layer 2 as shown in FIG.2. FIG. 1 shows a top end and a bottom end of the bent circuit wiringpatterns 3.

The outer surfaces of these circuit wiring patterns 3 are covered with asurface protecting layer 4 made of an appropriate insulating film or aphotosensitive resin. In the positions shown in FIG. 2, holes 5 whichpartially expose the circuit wiring patterns 3 are formed in the surfaceprotecting layer 4. The holes 5 are filled with a conductive metal by aplating means or the like, so that the ends on one side thereof areelectrically connected to the circuit wiring patterns 3 and the ends onthe other side thereof form bumps 6 which appropriately jut out of thesurface protecting layer 4.

These bumps are provided so that they are pressed to be electricallyconnected to the terminal formed on the end of a magnetic head madeintegral with circuit wiring which will be discussed later. The surfacesof the respective bumps 6, which provide such connecting terminals, maybe covered with a corrosion-resistant metal film such as gold plating.

As illustrated in FIG. 3, in such a magnetic head junction board 8, theedges of the springy metal layer 2 are bent to the U shape or the like.The aforesaid four bumps 6 are provided on each of the opposed surfacesof the bent portions. The magnetic head junction board 8 further has theflexible circuit board which integrally extend outward from the centerof the springy metal layer 2 and the terminal of the flexible circuitboard is electrically connected to the read/write amplifier substratewhich is not shown.

FIG. 3 is used to describe the connection between the magnetic headjunction board 8 in accordance with the present invention and themagnetic head suspension having circuit wiring as an integral piece. InFIG. 3, reference numeral 9 denotes an end of a swinging support arm.The ends of magnetic head suspensions 10 made integral with circuitwiring are connected to both surfaces of the end of the swinging supportarm 9 by crimping, spot welding, or the like; magnetic head sliders 11and 12, which have magnetic head devices, are attached separately to theouter faces of the distal end of the magnetic head suspensions 10.

The outer surfaces of the magnetic head suspensions 10 are providedintegrally with an appropriate number of wiring patterns required forthe magnetic head devices via appropriate insulating layers. Althoughthe surfaces of the wiring patterns are covered with appropriate surfaceprotecting layers, the ends of the wiring patterns are terminated asfour exposed terminals 13 at the portions close to the end of theswinging support arm 9 as illustrated. Thus, when the magnetic headjunction board 8 in accordance with the present invention is installedat the location where the terminals 13 of the magnetic head suspension10 made integral with circuit wiring are formed as illustrated in FIG.3, the clamping force of the springy metal layer 2 causes the respectiveterminals 13 associated with the respective bumps 6 to be connectedunder pressure, thereby achieving secure electrical connection betweenthe magnetic head suspensions 10 made integral with circuit wiring andthe read/write amplifier substrate via the magnetic head junction board8.

FIG. 4A through FIG. 4D show the manufacturing process steps accordingto an embodiment for fabricating the magnetic head junction board 8 inaccordance with the present invention; the manufacturing processdiagrams are taken on line Y--Y shown in FIG. 1.

In FIG. 4A, the laminated plate is prepared, in which one surface of theflexible insulating base material 1 has the springy metal layer 2 madeof a phosphor bronze plate or stainless plate or the like and the othersurface has the conductive layer made of copper foil or the like. Thedesired circuit wiring patterns 3 are formed on the conductive layer ofthe laminated plate by photoetching and the springy metal layer 2 isalso etched to the predetermined configuration.

In the next step, as illustrated in FIG. 4B, the outer surfaces of thecircuit wiring patterns 3 are provided with the surface protecting layer4 using an appropriate insulating film or a photosensitive resin. Theholes 5 are formed in the surface protecting layer 4 at the locationswhere the bumps, which will be discussed later, will be formed so thatthe circuit wiring patterns 3 are partially exposed. The desired surfaceprotecting layer 4 is produced by applying a photosensitive resin suchas a photosensitive polyimide resin, photosensitive epoxy resin,photosensitive acrylic resin, or the like, then drying, exposure,developing, and curing in the order in which they are listed.

As illustrated in FIG. 4C, the holes 5 in the surface protecting layer 4are filled with an appropriate conductive metal by plating or the like,so that the ends on one side thereof are electrically connected to thecircuit wiring patterns 3 and the ends on the other side thereof formthe bumps 6 which appropriately jut out. As necessary, the surfaces ofthe bumps 6 may be provided with a corrosion-resistant metal film bygold plating or the like.

Lastly, after shaping the unit to the predetermined configuration, theedges of the springy metal layer are bent inward to a U shape so thatthe bumps 6 on both ends face against each other as illustrated in FIG.4D to complete the magnetic head junction board 8 in accordance with thepresent invention.

FIG. 5A through FIG. 5E show the manufacturing process steps accordingto another embodiment for fabricating the magnetic head junction board 8in accordance with the present invention. As in FIG. 4, themanufacturing process steps shown in FIGS. 5A through 5E also show theviews taken along line Y--Y of FIG. 1. This manufacturing process iseffective for achieving a smaller junction board while improving theoutline machining accuracy at the same time.

In this embodiment, firstly, as shown in FIG. 5A, the laminated plate isprepared, in which one surface of the flexible insulating base material1 has the springy metal layer 2 made of a phosphor bronze plate orstainless plate or the like and the other surface has the conductivelayer made of copper foil or the like. The desired circuit wiringpatterns 3 are formed on the conductive layer of the laminated plate byphotoetching and grooves 7 of predetermined shapes are etched in thespringy metal layer 2.

According to the similar process shown in FIG. 4B and FIG. 4C, thesurface protecting layer 4, which has the holes 5, and the bumps 6 areformed in sequence.

Then, as illustrated in FIG. 5D, excimer laser beam A is radiated fromthe side of the springy metal layer 2 while utilizing the springy metallayer 2 as a light shielding mask, thereby ablating the portions of theflexible insulating base material 1 and the surface protecting layer 4,which correspond to the areas of the grooves 7, so as to obtain theshape of the unit.

Lastly, as shown in FIG. 5E, the edges of the springy metal layer 2 isbent inward into the U shape so that the bumps 6 on both ends faceagainst each other. This completes the magnetic head junction board 8 inaccordance with the present invention.

The magnetic head junction board in accordance with the presentinvention has the flexible circuit board which has a required number ofconnecting terminals which jut out in bumps at the locations on theinner side ends of the springy metal layer which has been bent into theU shape so that the bumps face against each other. This makes itpossible to easily accomplish the electrical connection between the bumpconnecting terminals and the terminals of the suspensions made integralwith the circuit wiring by utilizing the clamping force of the springymetal layer.

Thus, applying the magnetic head junction board to a magnetic recordingunit which employs a suspension made integral with the circuit wiringeliminates the inconvenient wire connection between the circuit wiringof the suspension and the read/write amplifier substrate as in theconventional unit. This permits automated assembly of the unit, thusenabling stable supply of inexpensive magnetic recording units.

What is claimed is:
 1. A manufacturing method for a magnetic headjunction board, the board being employed for electrically connecting amagnetic head suspension to a circuit wiring pattern on a read/writeamplifier substrate, said method comprising the steps of:preparing alaminated plate, in which one surface of a flexible insulating basematerial abuts a springy metal layer and the other surface supports aconductive layer; forming a circuit wiring pattern from the conductivelayer of said laminated plate and forming said springy metal layer intoa predetermined shape; providing the outer surface of said circuitwiring pattern with a surface protecting layer which has holes to partlyexpose ends of the circuit wiring pattern at the portions thereof whichcorrespond to both ends of said springy metal layer; filling said holeswith conductive metal to form connecting terminals, first ends of saidterminals being electrically connected to said circuit wiring patternand the opposite ends of said terminals projecting outwardly beyond thesurface of said protecting layer; and bending said springy metal layerto a predetermined shape so that said connecting terminals at said endsof said metal layer face each other.
 2. The manufacturing method for amagnetic head junction board according to claim 1, wherein said surfaceprotecting layer is produced by successive steps of applying aphotosensitive resin on said outer surface of said circuit pattern;drying said photosensitive resin; exposing the dried photosensitiveresin; developing the exposed photosensitive resin and thereafter curingthe developed photosensitive resin.
 3. The manufacturing method for amagnetic head junction board according to claim 2, wherein saidconnecting terminals are formed into bumps by plating said projectingopposite ends with a conductive metal.
 4. The manufacturing method for amagnetic head junction board according to claim 3, further comprisingthe step of providing the outer surfaces of said bump-shaped connectingterminals with a corrosion-resistant metal film.
 5. The manufacturingmethod for a magnetic head junction board according to claim 1, whereinsaid connecting terminals are formed into bumps by plating saidprojecting opposite ends with a conductive metal.
 6. The manufacturingmethod for a magnetic head junction board according to claim 5, furthercomprising the step of providing the outer surfaces of said bump-shapedconnecting terminals with a corrosion-resistant metal film.
 7. A methodfor the manufacture of a magnetic head junction board for electricallyand mechanically coupling a magnetic head suspension to a circuit wiringpattern of a read/write amplifier substrate, said method comprising thesteps of:preparing a laminated plate, in which one surface of a flexibleinsulating base material abuts a springy metal layer and the othersurface of said base material supports a conductive layer, said metallayer having a pair of opposite ends; forming a desired circuit wiringpattern on the conductive layer of said laminated plate and forming agroove, which matches a predetermined contour, in said springy metallayer; providing the outer surface of said circuit wiring pattern with asurface protecting layer, said protecting layer having holes to partlyexpose the ends of the circuit wiring pattern at the portions whichcorrespond to both ends of said springy metal layer; filling said holeswith conductive metal to form connecting terminals first ends of saidterminals being electrically connected to said circuit wiring patternand the opposite ends of said terminals projecting outwardly beyond thesurface of said surface protecting layer; employing an excimer laserbeam to ablate the portions of said flexible insulating base materialand the surface protecting layer which are positioned in the area ofsaid groove so as to obtain a predetermined configuration; and bendingsaid springy metal layer to a predetermined shape.
 8. The manufacturingmethod for a magnetic head junction board according to claim 7, whereinsaid surface protecting layer is produced by sequentially carrying outthe application of a photosensitive resin, drying, exposure,development, and curing.
 9. The manufacturing method for a magnetic headjunction board according to claim 7, wherein said outwardly projectingopposite ends of said connecting terminals are formed into bumps byplating with a conductive metal.
 10. A manufacturing method for amagnetic head junction board according to claim 9, further comprisingthe step of providing the outer surfaces of said bump-shaped connectingterminals with a corrosion-resistant metal film.
 11. The manufacturingmethod for a magnetic head junction board according to claim 7, whereinsaid outwardly projecting opposite ends of said connecting terminals areformed into bumps by plating with a conductive metal.
 12. Themanufacturing method for a magnetic head junction board according toclaim 11, further comprising the step providing the outer surfaces ofsaid bump-shaped connecting terminals with a corrosion-resistant metalfilm.